1. Field of the Invention
This invention relates to snowplows, and particularly to snowplow deflectors.
2. Background of the Invention
Snowplow deflectors, also known a moldboard extensions, have been attached to upper edge of snowplows to increase the working surface of the plows and to thereby reduce the tendency of the plowed snow to blow onto the windshield of the vehicle. For example, U.S. Pat. Nos. 2,160,973 issued to Litchy and 2,103,775 issued to Frink disclose pivotally mounted boards attached atop a snowplow. These deflectors are not efficent under varied operating conditions and are inadequate in terms of operating life and vibration stability even under normal snowplow operating conditions. Under modern snowplowing practice roads are plowed frequently at high speeds before the snow accumulates. The high plowing speeds together with surface irregularities cause extreme vibrations to be generated in the snowplowing equipment. As a result, rigid deflectors are subject to premature vibration induced failure and also aggravate the already extreme vibrations experienced by the entire snowplow. Thus, the rigid deflectors, usually pivotally mounted, vibrate and chatter at high operating speeds or during severe weather conditions resulting in early failure both of the deflector and the entire snowplow assembly due to harmonic vibrations transmitted to the rest of the plowing apparatus from the deflector.
While some of these deflectors are adjustable from a position along the working surface of the snowplow blade to a retracted position in response to snow buildup they are generally not capable of adjusting their curvature gradually to adapt to varied conditions. As a result when plowing conditions are most severe the blades retract resulting in little improvement in visibility for the operator.
U.S. Pat. Nos. 3,429,059 and 3,413,738 relate to snowplows and U.S. Pat. Nos. 4,043,587 and 2,515,604 relate to flexible, automobile bug deflectors.
Despite many advances in the field of snowplow deflectors, the snow plowing art still lacks a deflector effective to control the flow of snow over the blade obscuring the operator's sight while increasing plowing efficiency by extending the working surface of the snowplow. In addition, the prior deflectors have a short working life. Moreover, the rigid deflectors, rather than aiding in the control of snowplow vibration in fact augment the vibrations experienced by the plow in use, thereby decreasing the efficiency and life of the entire plow assembly.